The subject matter described herein relates generally to methods and systems for handling wind turbine rotor blades and mounting said rotor blades on a wind turbine, and more particularly, to a handling device for lifting and aligning said rotor blades, for example with a crane, and to related methods.
At least some known wind turbines include a tower and a nacelle mounted on the tower. A rotor is rotatably mounted to the nacelle and is coupled to a generator by a shaft. A plurality of blades extends from the rotor. The blades are oriented such that wind passing over the blades turns the rotor and rotates the shaft, thereby driving the generator to generate electricity.
Modern wind turbines typically have a rotor with a considerable diameter and weight. The diameter of modern rotors may be larger than 120 meters and the weight of the rotor including a wind turbine hub and, for example, three wind turbine blades may add up to 50 tons or more. Accordingly, mounting of wind turbine typically requires expensive work equipment and the duration of the assembly period is a significant cost factor, in particular for off-shore wind turbines. Mounting the wind turbine could include the steps of transporting the different elements to the site of the wind turbine, assembling the tower sections and/or erecting the tower on ground or on a floating platform, pre-mounting the wind turbine hub on the nacelle, lifting the wind turbine nacelle with a crane and mounting the nacelle on the top of the tower. Thereafter, the blades may be successively fastened to a hook block of the crane by means of ropes or a holding apparatus, lifted to a position next to and mounted to the hub.
Due to the large exposed surface of the rotor blades, even small gusts of wind may have a large effect on the position of the rotor blade during lifting. Since wind turbines are installed in regions which are particularly exposed to wind, raising the blades into their assembly position may be tedious.
For blade mounting, the rotor blade is typically fastened to the hub with a large number of screws or bolts protruding out of a root section of the rotor blade. Prior to fastening, the rotor blade is typically to be aligned exactly to a bearing surface and to a pattern of holes in the hub. When the rotor blade approaches its assembly position, special care is typically to be taken to avoid that the bolts damage the rotor and/or the nacelle, which are typically made of a composite.
All this typically causes substantial time losses, which increase the assembly period and thus the costs for manpower and the expensive work equipment.
In view of the above, there is a desire for methods and tools that allow for reducing mounting time of wind turbine rotor blades.